Digital maps are used, in particular, but by no means exclusively, for the operation of navigation devices. In digital maps that can be used in navigation devices, it is also possible to graphically illustrate text messages such as, in particular, street names in addition to the geographic area. In order to illustrate the changes of position on the display unit of a navigation device in real-time while the navigation device is in motion, the limited computing capacity of navigation devices makes it necessary to pre-process the data of the digital maps in such a way that the least computing capacity possible is required during the operation.
In generic methods for generating digital maps, fixed positions are assigned to the text messages in a pre-processing step such that the text messages are always illustrated in the digital map at the same geographic position and it is no longer necessary to calculate the positions for the illustration of text messages during the operation.
The disadvantage of this prior art can be seen in that the text messages may overlap. Consequently, a certain degree of computing capacity is once again required in order to eliminate overlaps or to decide which text messages should be displayed. The calculation of the overlaps during the operation of a navigation device may result in one and the same text message consistently disappearing and reappearing on the display unit of the navigation device within very short intervals or in the computer unit of the navigation device being overloaded and thusly causing a stagnant illustration on the display unit.